The 13" Cobra style brakes from DoctorDiff do use the 73+ Mopar spindle, so, it might be possible. Of course it would leave about an inch of the outer rotor uncovered, and you'd probably have to modify the area around the caliper. You might also have to trim back the area where the caliper mounts attach, as they'd add a little to the thickness there and that might alter the caliper spacing. If you look at the pictures of the kit at DoctorDiff's website you'll see what I mean.
I haven't really given it much thought. It won't help my sale any, but I'm not really a big believer in disk brake dust shields.